Dopaminergic (DA) systems: their role in pathological neurobehavioral symptoms

Two established dopamine (DA) systems (i.e., the nigrostriatal and the mesolimbic-mesocortical) are the focus of this article. Their neuroanatomy is briefly outlined to relate neurochemical with neurobehavioral events and alterations in DA-affected systems with the behavioral consequence. Selected theories and major ideas related to DA systems and their implicated role in neurobehavioral symptoms that have emerged over the last decade are included. Correlations with behavioral consequences of disturbances in DA systems lack clarity as to precisely known clinical effects relating to human behavioral and motor acts. The purpose of this article is to review selectively the literature pertaining to two of the six major DA mechanisms. The principal question addressed in this article is, "How do DA mechanisms promote neurobehavioral consequences such as the symptoms of schizophrenia?" Other topics covered include Parkinson's disease, Huntington's chorea, and intracranial self-stimulation drive-reward mechanisms. These clinical features and their possible underlying basis are discussed in terms of evidence suggesting that DA neurotransmitter alterations are likely to be several steps removed from a primary causal locus, which has more than one biochemical or neurotransmitter mechanism.